Calibration curve protein electrophoresis

Figure 12.12b illustrates the application of gel electrophoresis to protein characterization. In this illustration a cross-linked polyacrylamide gel is the site of the electrophoretic migration of proteins that have been treated with sodium dodecyl sulfate. The surfactant dissociates the protein molecules into their constituent polypeptide chains. The results shown in Figure 12.12b were determined with well-characterized polypeptide standards and serve as a calibration curve in terms of which the mobility of an unknown may be interpreted to yield the molecular weight of the protein. As with any experiment that relies on prior calibration, the successful application of this method requires that the unknown and the standard be treated in the same way. This includes such considerations as the degree of cross-linking in the gel, the pH of the medium, and the sodium dodecyl sulfate concentration. The last two factors affect the charge of the protein molecules by dissociation and adsorption, respectively. Example 12.5 considers a similar application of electrophoresis. 

Figure 26-38 Calibration curve for protein molecular mass in sodium dodecyl sulfate-capillary gel electrophoresis. The abscissa, fre, Is the migration time of each protein divided by the migration time of a small dye molecule. [Data from j. K, Grady, J. Zang, t. M. Laue, RArosio, and N. D, Chasteen, "Characterization of the H- and L-Subunlt Ratios in Ferritins by Sodium Dodecyl Sulfate-Capillary Gel Electrophoresis," Anal. Biochem. 2002,302.263.)...

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